This invention relates to a method for closing with a cover a container for the final storage of radioactive substances, wherein the container and/or cover consist of a ceramic or metallic material.
Such a method is known from KfK 3000, September 1980--"Comparison of the various alternative shielding methods and evaluation of their practicability"--and Study "Alternative shielding methods", Nuclear Research Centre, Karlsruhe. In this method, an aluminium oxide container having an open edge extending at right angles to the axis of the container and a hemispherical cover of aluminium oxide are connected to each other. When the seating area of the cover is in engagement with the seating area of the container, the container and cover are secured together by the so-called "HIP Process" (Hot Isostatic Pressing). A compressing press fitted with a special furnace is necessary for this process. In order to achieve a leak-free connection between the container and cover, a temperature of around 1350.degree. C. and a pressure of at least 70 MPa is necessary. The high temperature and high amounts of energy are not without problems for the properties of the radioactive substances packed into the container, particularly if temperature-sensitive inner containers are used. Furthermore, a low stress condition in the joint area leading to a unitary structure of the cover and container can only be achieved by precise temperature control during cooling. This process is too expensive for series packing in hot cells and is therefore uneconomic.
The object of the present invention is to produce a method for gastight sealing of the type first referred to above, which can be used with sealing temperatures which are harmless to the packed radioactive substances and to the container, and at atmospheric pressure.